Load transfer unit



June 11, 1946. l J. H. JAcoBsoN LOAD TRANSFER UNIT Filed Dec. 29, 1943 Patented June 11,1946

UNITED STATES PATENT OFFICE LOAD TRANSFER UNIT James H. Jacobson, Chicago, Ill.

Application December 29, 1943, Serial No. 516,019

(Cl. .S4-47) 7 Claims. 1

which introduce excessive irregularities in the surface contour of the unit sections and which may under varying conditions of stress and resultant vibration act as focal points in the initiation of disintegrating or funneling action.

The special features of the present invention are directed to the provision of a stake or spike depending from the upper portion of the unit in position to be driven into the subgrade and to the further provision of an upwardly extending arm which affords a driving head adapted to receive the blows of a hammer or mallet in driving the stake into position.

Further objects and details will appear from a description of the invention in conjunction with the accompanying drawing wherein,

Figure 1 is a side elevation of the unit installed as a contraction joint;

Fig- 2 is a longitudinal sectional view of the twosections of the unit, temporarily united by an easily frangible bolt for shipment and in condition to be installed as an eXpansion joint;

Fig. 3 is an inner end elevation of one of the unit sections;

Fig. 4 is an inner end view of the thin metal 35 cap; and

Fig. 5 is an edge view of the lower or stake portion of a modified form of section.

TheV unit as a whole consists of two sections Ill,

which are preferably malleable iron castings, and

since the two are duplicates, a description of one `will suilicel for both. The sections stand in opposed relation to one another on opposite Ysides ofthe joint gap with their inner ends exposed in flush relation to the face of the concrete slab Within which the section is embedded. K

Each section is integrally formed to provide a backwardly extending body portion I I, embedded save' :forv itsinner face, in the concrete, a vertical standard I2 having its rear face and edges embedded, and a downward extension in the form of a tapered stake I3 adapted to be driven into the vsubgradel lTheV bodyportion is of reduced circular cross cross section at its rear end I5, but with the axes of successive cross sections lying in an obliquely downwardly and backwardly extending line, which gives to the body a conoidal formation presenting a horizontal medial profile I6 along its upper surface and an oblique medial profile II along its lower medial surfaceso that the contour of the body as a whole gives it the characteristics of a wedge, progressively enlarging toward its rear end but presenting an upper surface which along its longitudinal center line is normal to downwardly directed pressure lines. Moreover, the contour of the entire upper surface is such as to minimize the wedging tendency to produce longitudinal displacement under vertical stress, while the under surface which is free from vera tical stress, is so configured as to increase its anchoring effect.

The under surface of the body being obliquely disposed to the horizontal in substantial degree along its medial profile when embedded, affords substantial resistance to longitudinal displacement while the rear 'wall surface of the body is planate and without lateral extensions which, if present, might tend, under vibration, to dig into and abrade or wear away the adjacent concrete.

At the forward inner end of the body are two symmetrically disposed laterally projecting fins I8, the forward ends of which lie flush with the inner face of the body while the rear ends taper down and merge into the curved wall surface near the middle on each side.

The body of each unit section is provided from end to end with a vbore I9 which runs parallel with the upper medial prole, and the bores of the unit sections are aligned to receive a dowel 20 which is of a length to extend at each end beyond the companion bodies, even when separated to the degree shown in Fig. 1. Each of the bodies at its rear end is shouldered concentrically with the bore to provide a reduced flange 2! and onto one of the flanges so formed, is fitted a cap 22 of thin metal having a cylindrical body 23 of a size to provide a sliding iit around the protruding end of the dowel and of a length slightly greater than the maximum protrusion of the dowel, so as to provide within the concrete of one of the slabs avoid or cavity adapted to permit movement of the dowel within said void to allow for expansion and contraction of the concrete due to changes in temperature,

The cap is closed at its rear end 24 and oiiset at its forward end 25 to closely fit upon the ilange 2|, and in order to temporarily hold the dowel section at its inner end I4 and enlarged circular 55 and the unit section in proper relation to one another, the cap is indented at 26 to provide a fragile abutment for the end of the dowel at a point well in advance of the closed end of the cap.

.The opposite end of the dowel projects beyond the end of the body f the companion unit section, so that, when the concrete is poured, it will impinge directly against the exposed end of the dowel and embed the same against movement together with the'associated unit section. l

Each unit section is carried by its standard I2 which at its upper end has a width substantially equal to the diameter of the forward end of the body, exclusive of the fins I8. The standard is of slightly increasing width toward its lower -end where it merges into the downwardly projectingk stake I3 which tapers to a blunt point and is rof a length sufficient to permit driving into the subgrade to the extent required t0 Vbring the body of the unit section to the intended level. If desired the standard at its point of juncture with the stake can be provided with a rearwardly extending foot 2'! to gauge the elevatio-n of the body above the subgrade, but the provision of such a foot is optional and it can be omitted in cases where it is desirable to 'drive units of the same size to different levels to meet local conditions.

In order to facilitate the driving in of the stakes the unit section is provided with an upwardly extending arm 28, the inner face o'f which lies flush with the standard lat -the inner end ofthe body, and terminates at its upper end in a rearwardly extending flange affording a driving head 29 adapted to afford a sufficiently extended flat surface to receive the impact of a hammer or Sledge. l In order to unite the sections temporarily in close face Contact with one another, an aperture 3E) is provided in each section to "receive a small fragile headed bolt 3| and nut 32 which will be easily ruptured when the sectionsv are embedded and subjected to the strains caused by the contraction of the concrete and the widening of the gap between the faces of the concrete slabs.

When the unit is to be employed as a conn traction joint the parts are adjusted as in Fig. l,

with a wide gap between the opposed faces vof the unit sections and the uncapped end of the dowel protruding but slightly from the associated -body section. In this case in the event of contraction of the gap, due to expansion of the concrete, the capped end of the dowel will be free to move'within `the recess afforded within the cap,Y while the opposite uncapped end of the dowel will move in unison with the unit section through which it is entered. The indentation 26 in the fragile wall of the cap affords merely a temporary obstruction which will be sheared away as the dowel slides toward the end of the cavity afforded by the cap.

When the unit is used as an expansion joint, the faces or" the `unit sections will initially lie close together on opposite sides of a narrow gap and with the uncapped end of the dowel protruding to a substantial degree. In such case, -as the concrete contracts, and the `gap increases in width, the bolt 3| will be ruptured and the capped end 0f the dowel will permit the associated unit section to move along the dowel to the necessary extent. I

The provision of the stake in facial alignment with the standard and the upwardly extending headed arm, affords simple and effective means for rmly positioning the yunit sections at the ,required elevation prior vto the pouring o`f the concrete while the alignment of 'the'sep'arts of the structure enables the 'driving :impact to 'be desired length since the degree of protrusion of the ends of the dowel from the bodies of the unit sections can be varied to meet diverse conditions. Although I have described a dowel which is formed separately from the respective sections and which when in use is inimovably held within one of the sect-ions, it is obvious that the dowel might be permanently united therewith without materially modifying the structure or function of the device as a whole. v

Although it is preferred to configure the entire section as an integral casting, it is possible'to form the standard with its upper arm and depending stake from flat metal plate and to -weld the same to the forward end of the body so that in the claims it will be understood that the units are not necessarily of integral construction unless otherwise indicated.

Where I employ the term conoidal, I do not intend to limit the claims to a body structure in Awhich the cross diameter at any point `is truly circular, since the term is intended to define and include ovate, elliptical or similar forms which involve a departure from 'true ci'rcularity'.

I claim: Y

1. In a load transference deyice, a unit vsection consisting of a body having secure to vits lur'ider side a standard of a length to support the body at the intended elevation above the subgrade'and having in line with the standard a depending extension forming a stake adapted to be 'percussively driven into the Subgrade, the body being also provided with an upwardly extending driving arm aligned with the standard andV the stake adapted to receive a driving impact, and a dowel carried by the body and extending inwardly b'eyond the front end thereof.

2. In a load transference device, a unit section consisting of a body of conoidal formation enlarging from the inner frontend toward the rear Vend and having at'its inner front end a standard of a length to support the body at the intended elevation above the subgrade and having in line with the standard a depending extension forming a stake adapted t0 be percussively driven into the subgrade, the body being also provided with an upwardly extending driving arm aligned vwith the standard and theV stake adapted to receive a driving impact, and a' dowel carried' by the'body and extending inwardly beyond the yfront en 'd thereof.

3. In a load transference deviceVaunit "section consisting of abody 'having fat itsinner front end a standard of a length Vto stand in 'flush 're'lation to the farce of 'a concrete slabf'andsupp'rt the bodyat rthe intended elevation above "the 'subgrade and vl'ia'ving in line with'tile 'standard "a depending extension forming a stake adaptedto be percussively driven into the subgrade, rthe' body being .also providedf with an `upwardly extending driving arm 'aligned with 'the 'standard 'and 'the Y the open ended bores through the two unit sections permit the use of dowels of any stake adapted to receive a driving impact, and a dowel carried by the body and extending inwardly beyond the front end thereof.

4. In a load transference device, a unit section consisting of a body of conoidal formation enlarging from the inner front end toward the rear end and having at its inner front end a standard of a length to stand in flush relation to the face of a concrete slab and support the body at the intended elevation above the subgrade and having in line with the standard a depending extension forming a, stake adapted to be percussively driven into the subgrade, the body being also provided with an upwardly extending driving arm aligned with the standard and the stake adapted to receive a driving impact, and a. dowel carried by the body and extending inwardly beyond the front end thereof.

5. In a load transference device, a unit section consisting of a body having at its inner front end a standard of a length to stand in ush relation to the face of a concrete slab and support the body at the intended elevation above the subgrade and having in line with the standard a depending extension forming a stake adapted to be percussively driven into the subgrade, the body being also provided with an upwardly extending driving arm aligned with the standard and the stake and .provided with an enlarged driving head adapted to receive a driving impact, and a dowel carried by the body and extending inwardly beyond the front end thereof.

6. In a load transference device, a unit section consisting of a body of conoidal formation enlarging from the inner front end toward the rear end and having at its inner front end a standard of a length to stand in ush relation to the face of a concrete slab and support the body at the intended elevation above the subgrade and having in line with the standard a depending extension forming a stake adapted to be percussively driven into the subgrade, the body being also provided with an upwardly extending driving arm aligned with the standard and the stake and provided with an enlarged driving head adapted to receive a driving impact, and a dowel carried by the body and extending inwardly beyond the front end thereof.

7. In a load transference device, a, first unit section consisting of a body having at its front end a standard of a. length to stand in ush relation to the face of a concrete slab and support the body at the intended elevation above the subgrade and having in line withV the standard a depending extension forming a stake adapted to be percussively driven into the subgrade, the

body being also provided with an upwardly eX- tending driving arm aligned with the standard and the stake and .provided with an enlarged driving head adapted to receive a driving impact, a second like unit section associated with the rst unit section, a dowel carried by the body of one section and extended therefrom through the body of the other section, and a frangible connection between the two sections at a point relatively close to the dowel.

JAlWES H. JACOBSO'N; 

